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The Sample Covariance
Hi again! I want to calculate the sample covariance but the only formula I
can find is COVAR and that formula seems to calculate the population covariance which differs slightly. Is there a ready made formula for sample covariance? If not, I need so summarize the products between each pair of observations after deducting their mean respectively. I understand that for a "simple product" you can use an array formula like {=sum(B3:B6*C3:C6)} However, I need to subtract the mean first from each pair....I tried with {=sum((B3-$B$10):(B6-$B$10)*(C3-$C$10):(C6-$C$10))} Well, didn't really beleive in it...but thought it was worth trying. Any better suggestions? Regards, /Lars |
#2
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The Sample Covariance
I agree, it is surprising that Excel does not have a sample covariance
funtion, but why would you want to calculate it from scratch? Why not just calculate COVAR*n/(n-1) ? Jerry Lars F wrote: Hi again! I want to calculate the sample covariance but the only formula I can find is COVAR and that formula seems to calculate the population covariance which differs slightly. Is there a ready made formula for sample covariance? If not, I need so summarize the products between each pair of observations after deducting their mean respectively. I understand that for a "simple product" you can use an array formula like {=sum(B3:B6*C3:C6)} However, I need to subtract the mean first from each pair....I tried with {=sum((B3-$B$10):(B6-$B$10)*(C3-$C$10):(C6-$C$10))} Well, didn't really beleive in it...but thought it was worth trying. Any better suggestions? Regards, /Lars |
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